Medical monitoring system having multiple communications channels

ABSTRACT

A device includes a patient-portable remote monitoring unit to monitor one or more physiological characteristics of an individual and convey information characterizing the one or more physiological characteristics to a remote station. The monitoring unit includes a transmitter system capable to employ a selected one of three or more different communications channels to convey the information to the remote station, and a selection unit to select from among the three or more different communications channels for conveying the information to the remote station.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §120:

as a continuation application to U.S. application Ser. No. 10/737,193,which issued on Oct. 31, 2006 as U.S. Pat. No. 7,130,396; and

as a continuation-in-part application to U.S. application Ser. No.09/841,133, which issued on Dec. 16, 2003 as U.S. Pat. No. 6,665,385.

Both the U.S. Pat. No. 7,130,396 and the U.S. Pat. No. 6,665,385 patentsare incorporated by reference herein in their entirety.

BACKGROUND

The following description relates to a medical monitoring system havingmultiple communications channels, e.g., for providing alternativeinformation pathways between a medical monitoring unit and a centralmonitoring station.

Advances in sensor technology, electronics, and communications have madeit possible for physiological characteristics of patients to bemonitored even when the patients are ambulatory and not in continuous,direct contact with a hospital monitoring system. For example, U.S. Pat.No. 5,959,529 describes a monitoring system in which the patient carriesa remote monitoring unit with associated physiological sensors. Theremote monitoring unit conducts a continuous monitoring of one or morephysiological characteristics of the patient, such as the patient'sheartbeat and its waveform, according to a medical condition of thepatient.

An objective of such portable monitoring systems is to establish contactwith a central; monitoring station (a.k.a., a central unit), which is inturn may contact with medical personnel and/or access the patient'smedical records. The ability to establish contact allows the centralunit to determine the existence of a medical emergency with the patient,and to render medical assistance to the patient during such anemergency. The ability to establish contact is also importantpsychologically to the patient, so that the patient knows that (s)he isnot alone or out of touch. The portable monitoring systems may establishone or more communication links to the central unit through telephoneland-lines, when the patient is in a location where land-line telephoneaccess is readily available or through the cellular telephone systemwhen land-line access is not available or an emergency suddenly occurs.

SUMMARY

The present inventors recognized that existing medical monitoringsystems may be hampered by the fact that cellular telephonecommunication links are not available in many parts of the United Statesand in other countries. This unavailability arises because the cellularsystem infrastructure is not in place in relatively remote areas andbecause cellular telephone signals will not penetrate into manystructures even if they are within the range of cellular telephonetransceiver cell sites. As a result, the remote monitoring unit isunable to communicate with the central unit from many locations. Thepatient is therefore unable to obtain emergency assistance in thoselocations, and consequently feels isolated. Accordingly, the inventorsdeveloped various systems and techniques that help ensure wide-areacommunication availability for remote monitoring units of medicalmonitoring systems.

The systems and techniques disclosed here may include variouscombinations of the following features.

In one aspect, a medical monitoring system includes a sensor unitconfigured to sense one or more physiological characteristics of apatient, a monitoring unit in communication with the sensor unit andoperable to communicate information relating to the sensed physiologicalcharacteristics to a central unit, and two or more communicationschannels operable to communicate between the monitoring unit and thecentral unit. The monitoring unit is operable to specify fortransmission a data set that is tailored to a particular communicationschannel to be used to communicate the information relating to the sensedphysiological characteristics to the central unit.

The tailored data set for transmission my be a subset of a full data setor may be information derived from a data set. More generally, thetailored data set may include a data set that is adapted according toone or more parameters of the selected communications channel.

The monitoring unit may further be operable to select a communicationschannel from among the two or more communications channel, for example,based on one or more predetermined criteria such the communicationschannels' relative availability, bandwidth, quality, latency, cost,reliability, and the like. The communications channels may include oneor both of wired and wireless communications channels and, further, mayinclude one or more of a land-line telephone network, a cellulartelephone network, a paging network and a packet-switched data network.

In another aspect, a portable medical monitoring unit may be controlledby receiving sensor data from a sensor, the received sensor datarepresentative of one or more physiological characteristics of a patientbeing monitored, selecting a communications channel from among multiplepotential communications channels, specifying a data set fortransmission to a central unit, the specified data set being adapted tothe selected communications channel, and transmitting the specified dataset over the selected communications channel to the central unit.

Selecting the communications channel from among the potentialcommunications channels may be based on one or more predeterminedcriteria such as the communications channels' relative availability,bandwidth, quality, latency, cost and reliability.

Specifying the data set for transmission to the central unit may includeadapting the data set according to one or more parameters of theselected communications channel. The specified data set for transmissionmay include a subset of a full data set or may be information derivedfrom a data set.

The systems and techniques described here may provide one or more of thefollowing advantages. For example, a medical monitoring system having aremote monitoring unit may provide enhanced communications coveragethroughout the United States and/or much of the world. Thiscommunications coverage may include a wide geographical area and/orlocations such as the interiors of buildings that are sometimesunavailable for cellular telephone coverage. This enhancedcommunications coverage increases the likelihood that the remotemonitoring unit will be able to communicate with the central unit underemergency conditions. Equally importantly, the patient being monitoredhas better peace of mind of knowing that (s)he is rarely, if ever, outof touch with medical assistance. The present approach may beimplemented relatively inexpensively, as it can rely on communicationsinfrastructure that already is in place and operating, and it may beadapted to new communications technologies that become available. Theremote monitoring unit can be made to work with this approach withlittle, if any, increase in size, weight, and/or power consumption tothe remote monitoring unit.

Other features and advantages will be apparent from the followingdescription taken in conjunction with the accompanying drawings and theclaims.

DRAWING DESCRIPTIONS

FIG. 1 is a schematic diagram of a medical monitoring system; and

FIG. 2 is a block flow diagram of a method of operating the multiplecommunication channels.

DETAILED DESCRIPTION

FIG. 1 depicts a medical monitoring system 20 that includes a sensorsystem 22 having a sensor for monitoring any of a variety ofphysiological characteristics associated with a patient, for example, aheartbeat waveform, blood pressure, brain signals, blood chemistry, andthe like. The sensor system 22 communicates with a remote monitoringunit (RMU) 24 that typically is either carried by the patient or isrelatively physically close to the patient. The communication betweenthe sensor system 22 and the remote monitoring unit 24 may be eitherwired or wireless, such as a short-range radio frequency link.

The remote monitoring unit 24 includes a microprocessor 26 incommunication with the sensor system 22. The microprocessor 26 performscomputations as may be necessary and oversees the operation of aportable-monitoring unit transceiver system 28 that is also a part ofthe remote monitoring unit 24. The portable-monitoring-unit transceiversystem 28 communicates with a central unit (CU) 30 having a central-unittransceiver system 32 that supports communications of the types found inthe portable-monitoring-unit transceiver system 28 and which will bediscussed subsequently. The central unit 30 also includes a central unitmicroprocessor 34 that coordinates the central-unit transceiver system32 and performs other analytical and control functions. The generalfeatures of a preferred form of the medical monitoring system 20, otherthan those to be discussed subsequently, are described in U.S. Pat. No.5,959,529, whose disclosure is incorporated by reference.

The portable-monitoring-unit transceiver system 28 includes athird-network transceiver 35. The third-network transceiver 35 may be atwo-way paging-network transceiver operable with the paging network.However, the third-network transceiver 35 may be of other types, such asa specialized emergency-network transceiver, a marine-networktransceiver, and the like. Alternatively, or in addition, thethird-network transceiver 35 may be configured to establish acommunication link by other available means, among others, such as wiredor wireless networks that implement communications protocols andstandards such IP (Internet protocol), WiFi (IEEE 802.11x), WiMax (IEEE802.16x), and/or GPRS (General Packet Radio Service). Moreover, thethird network transceiver may be configured to communicate over eithercircuit-switched networks (e.g., traditional telephone networks) or overpacket-switched data networks.

The example implementation shown in FIG. 1 includes the paging networktransceiver 36 and its antenna 38 that selectively establish athird-network link (in this case a paging network link) with the centralunit 30. The paging network transceiver 36 operates using the existingpaging network available throughout the United States and much of therest of the world. Communication with the paging network is available invirtually every part of the United States and in most parts of the restof the world. It is available in the open, inside buildings, inaircraft, and onboard ships. The paging network originally operatedunidirectionally with signals conveyed only from the satellite to thepaging unit, but it is now available in a bidirectional form assuggested by the term “transceiver”, an art-recognized contraction of“transmitter/receiver”. That is, the bidirectional paging transceiver 36may either receive information or send information, via the existingpaging system, to the central unit transceiver 32.

The portable-monitoring-unit transceiver system 28 further includes acellular telephone transceiver 40 and its antenna 42, which may serve asa primary wireless network transceiver. The cellular transceiver 40selectively establishes a cellular link with the central unit 30. Thecellular telephone transceiver 36 operates using the existing network ofcell sites available through much of the United States and some of therest of the world. Cellular communications links are operable in theopen, inside most automobiles within range of cell sites, and insidemany buildings, but are often not available in some buildings, inaircraft, or onboard ships. The cellular telephone transceiver 40 mayeither receive information or send information through the cellularnetwork to the central unit transceiver 32.

The portable-monitoring-unit transceiver system 28 further includes aland-line telephone transceiver 44 and its plug jack 46. The land-linetelephone transceiver 44 selectively establishes a land-line link withthe central unit 30. The land-line telephone transceiver 44 operatesusing the land-line system (which may also include microwave links ofthe land-lines and/or may provide one or more of POTS (Plain OldTelephone Service), DSL (Digital Subscriber Line) or ISDN (IntegratedServices Digital Network) service) available through much of the UnitedStates and much of the rest of the world. Land-line telephonecommunications links are available through telephone central switchingoffices wherever there is a plug connection, but the need for physicalaccess to a plug tends to limit the mobility of the patient. Theland-line telephone transceiver 44 may either receive information orsend information through the land-line system to the central unittransceiver 32.

FIG. 2 depicts a sequence of events that may occur when communication isrequired between the remote monitoring unit 24 and the central unit 30.A need for communications is first determined (sub-process 60). Thissub-process typically occurs when the remote monitoring unit 24determines that it needs to communicate with the central unit 30, but itmay also occur when the central unit 30 determines that it needs tocommunicate with the remote monitoring unit 24. The former case will bediscussed in detail, but the discussion is equally applicable to thelatter case.

The land-line transceiver 44 is used if the land-line link is available(sub-process 62). That is, the microprocessor 26 seeks to open aland-line communication link to the central unit 30 through theland-line transceiver 44. If there is no plug in the plug jack 46 or ifit is otherwise not possible or feasible to dial up the central unit 30,then the microprocessor 26 seeks to open a cellular link to the centralunit 30 through the cellular telephone transceiver 40 (sub-process 64).The use of the land-line transceiver 44 typically is preferred to theuse of the cellular telephone transceiver 40, because the land-linecommunication link tends to be more reliable, more secure, and usuallyless costly, if available.

If the communication link is established either through the land-linetransceiver 44 or the cellular transceiver 40, then the microprocessor26 uses a first processing routine stored therein that transmits a fulldata set through either of these wide-bandwidth communications channels.This is the desired operating mode of the medical monitoring system 20,because its full data capabilities may be employed.

However, as noted above, in some instances neither the land-line linknor the cellular link is available due to reasons such as unavailabilityof the land line, unavailability of the cellular system, user overloadof the cellular system, interference to wireless communications in thefrequency band of the cellular system, or the like. In that case, thethird-network transceiver 36 is used (sub-process 66) to employ analternative communications channel such as the paging network or anavailable wired or wireless packet-switched network, such as theInternet. If the third-network provides a reduced communicationsbandwidth, e.g., in comparison the cellular or land-lines networks, thenthe microprocessor 26 may use a second processing routine stored thereinthat determines and transmits a reduced data set over the paging-networklink. In some cases where the sensor system 22 obtains a small amount ofdata such as a single blood chemistry number, the full data set may betransmitted over the paging network transceiver 36. In other cases wherethe sensor system 22 obtains much larger amounts of data, such as aheartbeat waveform, then it may not be possible or feasible (e.g., dueto network latency or other delays) to transmit the full data set evenif data compression techniques are used. The second processing routineis written to select some subset of the data (e.g., the most important)that is gathered by the sensor system 22, and/or to calculate orotherwise generate secondary data from the gathered data (e.g., dataderived from, and representative of, the sensed data), for transmissionover the paging network transceiver 36. In the case of the heartbeat,for example, the second processing routine may calculate a heart rate(number of beats per minute), amplitude, and waveform characteristics ofselected portions of the full heartbeat signal for transmission withinthe bandwidth constraints of the third-network. The second processingroutine would typically not select voice or other audio signals fortransmission. This reduced data set, while not as complete as the fulldata set, is far better and more useful to the central unit 30 indiagnosing and aiding the patient than having no information and nocontact at all.

It is possible to perform multiple serial communications between theremote monitoring unit 24 and the central unit 30 to transmit moreinformation, but even in that case it is unlikely that the full data setcan be conveyed. The selection of the content of the reduced data set,and thus the content of the second processing routine, is left to theindividual situation and type of data being monitored for the individualpatient.

More generally, the transceiver system 28 of the remote monitoring unit24 may employ multiple (i.e., two, three, four or more) differentcommunications channels for communicating information from the remotemonitoring unit 24 to the central unit 30. The microprocessor 26 thencan rely on predetermined criteria (e.g., such as described in a table,database or software instructions) to select (and/or otherwisespecifying or generating) a data set for transmission that is tailoredto, or otherwise appropriate for, the particular communications channelbeing used. The predetermined criteria may be set or altered by a systemdesigner or administrator, or even by a software process automatically,depending on several different factors including the types ofphysiological characteristics being monitored, the severity of thepatient's condition, the available bandwidth, quality, latency, costand/or reliability of the communications channel to be used, and thelike.

The system described above may provide a communications hierarchy basedupon a recognition that limited communications is better than nocommunications in many instances, and a recognition of the tradeoffbetween factors such as communications availability and bandwidth. Somecurrently available communications links are summarized in the followingtable, with the land-line telephone being a wired connection and theother communications links being wireless. However, it is emphasizedthat the use of the systems and techniques described here is not limitedto these types of communications links and includes other presentlyavailable and future communications links: Center Frequency BandwidthCommunications Link (MHZ) (Qualitative) Land-line telephone — very highAnalog cellular phone 859 moderate Digital CDMA cellular phone 800 highDigital PCS CDMA cellular 1900  high phone Motorola Reflex paging 900moderate Celemetry paging 859 very low

Thus, in the implementation described above the portable-monitoring-unittransceiver system of the medical monitoring system includes theland-line telephone transceiver and a digital cellular transceiver.However, when communication over these communications links is notavailable, one or more of the alternative, third-networks (e.g., thepaging network) may be used as a backup. Even data communications over alow-bandwidth or moderate-bandwidth paging system is preferable to nocommunication in many situations.

Although a particular implementation been described in detail forpurposes of illustration, various modifications and enhancements may bemade, for example, by combining, rearranging or substituting differentfeatures or sub-processes for those disclosed above. Accordingly, otherembodiments are within the scope of the following claims.

1. A device comprising: a patient-portable remote monitoring unit tomonitor one or more physiological characteristics of an individual andconvey information characterizing the one or more physiologicalcharacteristics to a remote station, the monitoring unit including atransmitter system capable to employ a selected one of three or moredifferent communications channels to convey the information to theremote station, and a selection unit to select from among the three ormore different communications channels for conveying the information tothe remote station.
 2. The device of claim 1, wherein the transmittersystem comprises a first transceiver, a second transceiver, and a thirdtransceiver.
 3. The device of claim 1, wherein the transmitter systemcomprises packet-switched network transmitter.
 4. The device of claim 3,wherein the packet-switched network transmitter comprises a wirelesstransmitter.
 5. The device of claim 1, wherein the transmitter systemcomprises a pair of wireless transmitters and a single wiredtransmitter.
 6. The device of claim 1, further comprising a dataprocessing device to tailor the information characterizing the one ormore physiological characteristics based at least in part on one or morecharacteristics of the communications channel selected by the selectionunit.
 7. The device of claim 1, further comprising a data processingdevice to tailor the information characterizing the one or morephysiological characteristics based at least in part on thephysiological characteristics of the individual being monitored.
 8. Thedevice of claim 1, further comprising a data storage device to store theinformation characterizing the one or more physiological characteristicsin anticipation of transmission.
 9. The device of claim 1, wherein thepatient-portable remote monitoring unit comprises a cardiac monitoringunit to monitor electrical characteristics of a heart.
 10. A methodcomprising: monitoring one or more physiological characteristics of anindividual with a patient-portable device; selecting a firstcommunication channel from among a collection of three or morecommunication channels for communicating information characterizing theone or more physiological characteristics of the individual; andtransmitting information characterizing the one or more physiologicalcharacteristics to a remote station.
 11. The method of claim 10, whereinselecting the first communication channel comprises: determining that asecond communication channel is unavailable; and selecting the firstcommunication channel based at least in part on the unavailability ofthe second communication channel.
 12. The method of claim 11, whereindetermining that the second communication channel is unavailablecomprises determining that a land-line communication channel isunavailable.
 13. The method of claim 11, wherein selecting the firstcommunication channel further comprises: determining that a thirdcommunication channel is unavailable; and selecting the firstcommunication channel based at least in part on the unavailability ofthe third communication channel.
 14. The method of claim 10, whereinmonitoring the one or more physiological characteristics comprisescontinuously monitoring the one or more physiological characteristics.15. The method of claim 10, further comprising tailoring the transmittedinformation based at least in part on one or more characteristics of thefirst communication channel.
 16. The method of claim 10, furthercomprising tailoring the transmitted information based at least in parton the one or more physiological characteristics of the individual beingmonitored.
 17. A device comprising: a patient-portable remote cardiacmonitoring unit to monitor electrical characteristics of a heart; a linetransmission system to transmit information characterizing theelectrical characteristics of the heart to a remote station, the linetransmission system including a plug dimensioned to receive a tangibleline to connect to a first communication channel; a first wirelesstransmission system to transmit information characterizing theelectrical characteristics of the heart to the remote station, the firstwireless transmission system including a first wireless transmitter toconnect to a second communication channel; a second wirelesstransmission system to transmit information characterizing theelectrical characteristics of the heart to the remote station, thesecond wireless transmission system including a second wirelesstransmitter to connect to a third communication channel; and selectionlogic to select from among the first communication channel, the secondcommunication channel, and the third communication channel fortransmission of a set of information characterizing the electricalcharacteristics of the heart to the remote station based at least inpart on unavailability of one or more of the other communicationchannels.
 18. The device of claim 17, wherein the first wirelesstransmitter comprises a packet-switched network transmitter.
 19. Thedevice of claim 17, further comprising a data processing device totailor set of the information characterizing the electricalcharacteristics of the heart based at least in part on one or morecharacteristics of the communications channel selected by the selectionlogic for transmission.
 20. The device of claim 1, wherein thetransmitter system comprises wireless radio frequency transmitter. 21.The device of claim 20, wherein the wireless radio frequency transmitteroperates in accordance with IEEE 802.11.
 22. The method of claim 10,wherein transmitting information to the remote station comprisestransmitting the information over a point-to-point wireless connection.23. The method of claim 10, wherein transmitting information to theremote station comprises transmitting the information using a wirelessradio frequency transmitter.